ocr: (a) CFastString a=btc+d; 6) CStringSumn-CStringSum-CFastSitring, CFassirmgsCrastining I T b - (c). CStringSums - - - - - - piR - - CStringSums - - po - L - I - CFastString d CFastString CFastString I - C . d (a)The assignment expression. (b)The type pithervalue. (c) The expression tree defined by the type. Figure 2: The expression template parse tree